Editing ISRO (section)

=== Spacecraft propulsion and power ===
;Electric thrusters
{{Main|Spacecraft electric propulsion}}
India has been working on replacing conventional [[Spacecraft propulsion#Chemical propulsion|chemical propulsion system]] with [[Hall-effect thruster|Hall-effect]] and [[Pulsed plasma thruster|plasma]] thrusters which would make spacecraft lighter.<ref name="WIONMar21" /> [[GSAT-4]] was the first Indian spacecraft to carry electric thrusters, but it failed to reach orbit.<ref>{{cite news |url=http://www.thehindu.com/sci-tech/science/article399411.ece |title=Why didn't the cryogenic engine ignite? |last=Subramanian |first=T. S. |date=17 April 2010 |work=The Hindu |access-date=21 March 2021 |archive-date=13 November 2012 |archive-url=https://web.archive.org/web/20121113123805/http://www.thehindu.com/sci-tech/science/article399411.ece |url-status=live}}</ref> [[GSAT-9]] launched later in 2017, had [[xenon]]-based [[Spacecraft propulsion#Electric propulsion|electric propulsion system]] for in-orbit functions of the spacecraft. [[GSAT-20]] is expected to be the first fully electric satellite from India.<ref name="newsexpress">{{cite news |url=http://www.newindianexpress.com/states/kerala/ISRO-to-Test-Electric-Propulsion-on-Satellites/2015/11/30/article3153565.ece |title=ISRO to Test Electric Propulsion on Satellites |work=The New Indian Express |first=Tiki |last=Rajwi |date=30 November 2015 |access-date=21 March 2021 |archive-date=7 May 2016 |archive-url=https://web.archive.org/web/20160507084803/http://www.newindianexpress.com/states/kerala/ISRO-to-Test-Electric-Propulsion-on-Satellites/2015/11/30/article3153565.ece |url-status=dead}}</ref><ref>{{cite news |url=http://www.thehindu.com/sci-tech/science/gsat-9-heralds-cost-saving-electric-propulsion/article18347912.ece |title=GSAT-9 heralds cost-saving electric propulsion |work=The Hindu |last=D. S. |first=Madhumathi |date=1 May 2017 |access-date=21 March 2021 |archive-date=15 April 2021 |archive-url=https://web.archive.org/web/20210415023332/https://www.thehindu.com/sci-tech/science/gsat-9-heralds-cost-saving-electric-propulsion/article18347912.ece |url-status=live}}</ref>

On 28 March 2025, ISRO reported that its 300 [[Millinewton|mN]] xenon-based Stationary Plasma Thruster had successfully completed a 1,000-hour life test under 5.4 [[kW]] full power in a vacuum chamber. The electric propulsion system, which is intended to replace the chemical propulsion system in future satellites for [[orbit raising]] and [[orbital station-keeping]], is designed to incorporate SPT. It will enable [[Satellite bus|satellite buses]] to carry more transponders because of their reduced weight. Compared to the chemical propulsion system, the specific impulse of SPT is at least six times greater. The EPS will be utilized for orbit raising to the geostationary orbit and is intended to be introduced and validated in the next Technology Demonstration Satellite (TDS-01) mission.<ref>{{Cite web |date=28 March 2025 |title=ISRO successfully completes 1000hrs Life Test of Stationary Plasma Thruster for Spacecraft Electric Propulsion System |url=https://www.isro.gov.in/ISRO_successfully_conducts_1000hrs_life_test_of_SPT.html |access-date=2025-04-18 |website=www.isro.gov.in}}</ref><ref>{{Cite web |last= |date=2025-03-29 |title=ISRO successfully completes 1000-hr life test of Stationary Plasma Thruster for satellites |url=https://www.thehindubusinessline.com/business-tech/isro-successfully-completes-1000-hr-life-test-of-stationary-plasma-thruster-for-satellites/article69389132.ece |access-date=2025-04-18 |website=BusinessLine |language=en}}</ref>

;Alpha source thermoelectric propulsion technology
{{Main|Radioisotope thermoelectric generator}}
Radioisotope thermoelectric generator (RTG), also called alpha source thermoelectric technology by ISRO, is a type of [[atomic battery]] which uses nuclear [[decay heat]] from radioactive material to power the spacecraft.<ref name=NPE3>[https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Radioisotopes%20Power%20Production.pdf NPE chapter 3 Radioisotope Power Generation] {{webarchive |url=https://web.archive.org/web/20121218194925/https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Radioisotopes%20Power%20Production.pdf |date=18 December 2012 }}</ref> In January 2021, the [[U R Rao Satellite Centre]] issued an Expression of Interest (EoI) for design and development of a 100-[[watt]] RTG. RTGs ensure much longer spacecraft life and have less mass than solar panels on satellites. Development of RTGs will allow ISRO to undertake long-duration deep space missions to the outer planets.<ref name="RTEG" /><ref>{{Cite web |last=Bansal |first=Nitansha |title=ISRO plans for nuclear energy use in space |url=https://www.orfonline.org/expert-speak/isro-plans-for-nuclear-energy-use-in-space/ |url-status=live |access-date=19 May 2021 |website=Observer Research Foundation |language=en-US |archive-date=18 May 2021 |archive-url=https://web.archive.org/web/20210518140859/https://www.orfonline.org/expert-speak/isro-plans-for-nuclear-energy-use-in-space/}}</ref>

;Radioisotope heater unit
{{Main|Radioisotope heater unit}}
ISRO included two radioisotope heater units developed by the [[Department of Atomic Energy]] (DAE) in the propulsion module of [[Chandrayaan-3]] on a trial basis which worked flawlessly.<ref name=":1">{{Cite news |last=Laxman |first=Srinivas |date=29 December 2023 |title=Nuclear sector set to power Indian space missions: Isro chief |url=https://timesofindia.indiatimes.com/home/science/nuclear-sector-set-to-power-indian-space-missions-isro-chief/articleshow/106359396.cms |url-status=live |archive-url=https://web.archive.org/web/20240108154309/https://timesofindia.indiatimes.com/home/science/nuclear-sector-set-to-power-indian-space-missions-isro-chief/articleshow/106359396.cms |archive-date=8 January 2024 |access-date=29 December 2023 |work=[[The Times of India]] |issn=0971-8257 }}</ref>

;Nuclear propulsion
{{Main|Nuclear propulsion}}
ISRO has plans for collaboration with Department of Atomic Energy to power future space missions using nuclear propulsion technology.<ref name=":1" />